$ { \left[\begin{array}{rr}{-2} & {3} \\ {3} & {0} \\ {3} & {-1}\end{array}\right]+\left[\begin{array}{rr}{-1} & {-1} \\ {-2} & {2} \\ {-1} & {3}\end{array}\right] = {?} } $
To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{-2}+{-1} & {3}+{-1} \\ {3}+{-2} & {0}+{2} \\ {3}+{-1} & {-1}+{3}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-3} & {2} \\ {1} & {2} \\ {2} & {2}\end{array}\right]}$